Joseph Myers fa7f43a982 Support assert as a variadic macro for C23 ...

C23 makes assert into a variadic macro to handle cases of an argument
that would be interpreted as a single function argument but more than
one macro argument (in particular, compound literals with an
unparenthesized comma in an initializer list); this change was made by
N2829.  Note that this only applies to assert, not to other macros
specified in the C standard with particular numbers of arguments.

Implement this support in glibc.  This change is only for C; C++ would
need a separate change to its separate assert implementations.  It's
also applied only in C23 mode.  It depends on support for (C99)
variadic macros, and also (in order to detect calls where more than
one expression is passed, via an unevaluated function call) a C99
boolean type.  These requirements are encapsulated in the definition
of __ASSERT_VARIADIC.  Tests with -std=c99 and -std=gnu99 (using
implementations continue to work.

I don't think we have a way in the glibc testsuite to validate that
passing more than one expression as an argument does produce the
desired error.

Tested for x86_64.

2025-11-03 19:56:42 +00:00

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